FILE - In this Thursday, Nov. 5, 2009 file photo, Spc. Ryan Howard of Niles, Mich., right and Spc. David Straub of Ardmore, Okla. wait for news of fellow soldiers while waiting at the gate of the Army base after a shooting at Fort Hood, Texas. (AP Photo/LM Otero)— AP

FILE - In this Thursday, Nov. 5, 2009 file photo, Spc. Ryan Howard of Niles, Mich., right and Spc. David Straub of Ardmore, Okla. wait for news of fellow soldiers while waiting at the gate of the Army base after a shooting at Fort Hood, Texas. (AP Photo/LM Otero)
/ AP

FILE - In this Friday, Sept. 14, 2012 file photo, Libyan military guards check one of the U.S. Consulate's burnt out buildings during a visit by Libyan President Mohammed el-Megarif, not shown, to the U.S. consulate in Benghazi, Libya to express sympathy for the death of the American ambassador, Chris Stevens and his colleagues in the deadly Sept. 11, 2012 attack on the consulate. (AP Photo/Mohammad Hannon, File)— AP

FILE - In this Friday, Sept. 14, 2012 file photo, Libyan military guards check one of the U.S. Consulate's burnt out buildings during a visit by Libyan President Mohammed el-Megarif, not shown, to the U.S. consulate in Benghazi, Libya to express sympathy for the death of the American ambassador, Chris Stevens and his colleagues in the deadly Sept. 11, 2012 attack on the consulate. (AP Photo/Mohammad Hannon, File)
/ AP

FILE - In this Tuesday, Sept. 11, 2001 file photo, two women embrace each other as they watch the World Trade Center burn following a terrorist attack on the twin skyscrapers in New York. (AP Photo/Ernesto Mora) MANDATORY CREDIT— AP

FILE - In this Tuesday, Sept. 11, 2001 file photo, two women embrace each other as they watch the World Trade Center burn following a terrorist attack on the twin skyscrapers in New York. (AP Photo/Ernesto Mora) MANDATORY CREDIT
/ AP

The word is almost a cold comfort in post-9/11 America - a way to describe the inconceivable, to somehow explain the twisted urge to commit mass murder. So when the bombs exploded in Boston, the word quickly became inescapable: "terrorism."

Dictionaries, and people who study the age-old activity, define terrorism as the use of violence and fear to pursue political goals. But that definition may have expanded to fill a vacuum as the nation waits to learn a motive in the Boston Marathon explosions that killed three people and maimed scores more.

President Barack Obama chose not to use the word "terrorism" in his first remarks hours after Monday's bombing. "The word has taken on a different meaning since 9/11," Obama advisor David Axelrod explained on MSNBC.

"I'm sure what was going through the president's mind is, we really don't know who did this," Axelrod said on Tuesday morning.

But, in the public discussion, there was already a palpable hunger for the term. "All the right words but one," was the headline of an analysis by the Defense Media Network. "Only safe assumption: It was terrorism," another editorial was headlined in the Pittsburgh Post-Gazette.

Within hours of Axelrod's remarks, and with no suspects or motive announced, Obama said: "Any time bombs are used to target innocent civilians it is an act of terror."

In times of tension and uncertainty, words can become malleable vessels - for cultural fears, for political agendas, for ways to make sense of the momentous and the unknown. In 2013 America, the word "terrorism" exists at this ambiguous crossroads. And the opinions you'll find about it - this week in particular - often transcend mere linguistics.

Obama's conclusion about bombs and terror made perfect sense to Jay Winuk, whose brother, a lawyer and volunteer firefighter, died on September 11, 2001 while trying to evacuate the World Trade Center after it was attacked by fanatical Muslims.

"Based on what we know so far, I do consider it an act of terrorism," Winuk said Wednesday, before news broke of a possible suspect in the case. "I don't know that for me personally, political motivation is part of the equation."

"Whoever did this, it seems clear that their intention was to harm, maim, kill innocent people en masse who are going about their normal activity. To me, that's terrorism," said Winuk, a co-founder of "My Good Deed," a group that has established 9/11 as a national day of service.

But that definition was a bit premature for the high school seniors in Reba Petraitis' contemporary history class at Kent Place School in Summit, N.J.

Petraitis is part of the 4 Action Initiative, which responded to 9/11 by developing a statewide curriculum for teaching children about terrorism. Her class studies the many definitions used by various U.S. agencies and international governments and formed its own definition, which includes the intent to "intimidate, provoke a reaction or further an agenda."

On Wednesday, the students weighed Obama's remarks but were still not ready to call the Boston attack terrorism. Yet they understood why so many people were using the word, Petraitis said.